There is quite a useful tool
HERE which calculates the annual leave entitlement based on the number of days
or the number of hours worked each week.
For the current year, this will take some working out as the hours worked has changed mid-way through the year, and it will also depend on the period in which the employer calculates the holiday year (ie January - December, May - April etc) but basically in the year April 2007 to the end of March 2008, employees have to have a minimum of 4.4 x the normal number of hours worked each week, rising to 4.8 x the number of hours worked in the year April 2008 to March 2009. In 2009/10 the multiplier will rise to 5.6 weeks holiday. As stated this can include Statutory Public Holidays where they are not worked under the terms of her contract.